Nonrespiratory Functions of the Lung

Abstract

Pulmonary endothelial cells metabolize endogenous substances and xenobiotics via ectoenzymes on their luminal surface and caveolae as well as enzyme systems within the cytosol. Pulmonary metabolism results in the activation of several endogenous substances and medications of importance to the anesthesiologist. Pulmonary uptake is often not associated with metabolism, but still markedly affects pharmacokinetics by initially attenuating peak concentrations before ultimately returning the unchanged substance to the circulation. The lung’s ability to serve as a vascular reservoir is directly related to the capacitance of the pulmonary vessels. The lung serves as a physical filter, but this function may be compromised with high cardiac output and in several disease states. The respiratory epithelium’s functions include humidification and trapping of particles and pathogens. The airway surface film has antimicrobial capacity beyond its mechanical removal of debris from the airway.